Guide to Washers
Washers are multipurpose fasteners that are vital in a variety of applications. In general, washers have two main functions: to distribute the pressure of the nut evenly over a surface without damage, and to ensure that the nut is pressed against a smooth surface to reduce the chances of loosening over time.
Choosing the right washer for the task at hand first requires understanding the overall structure of the different kinds. Check out our fastener type chart:
| Name | Description | Shape | Use |
|---|---|---|---|
| Structural | Top-bearing surface is cut at an oblique angle to compensate for nonparallel surfaces | Round or square | Structural leveling and shimming applications |
| Conical or Spring | Slight dish shape and edges that are sheared parallel to the center line to increase elasticity of join | Round | Good for absorbing shock and maintaining tension under dynamic loads |
| Countersunk | Allows flat or oval head countersunk screws to be flush | Round | Allows for a finished appearance |
| Fender | Large outside diameter provides extra wide bearing surface | Round | Used to distribute force/stress and can cover oversized holes |
| Flat | The most common washer, with two flat surfaces | Round or square | Used to distribute force/stress of a nut or bolt and reduces friction and heat during installation of threaded fastener |
| Sealing | Made of relatively soft materials | Round | Forms a seal around a bolt or fastener and sometimes bonds to metallic washers |
| Slotted | Has a slot the same width as the hold diameter that is cut from the center to the perimeter | Round | Slips on and off shaft without removing the fastener |
| Spherical | Two piece equalizing assembly with one flat washer and one dish-shaped washer | Round | Eliminates unequal thread loads and stress from misaligned parts and nonparallel surfaces |
| Split Lock | Split with one end bent slightly outward to bite in and prevent loosening | Round | Acts like a spring under compression to provide extra holding force and decrease frictional resistance during assembly and disassembly |
| Tooth Lock | Has directional teeth or serrated edges, also referred to as star washers | Round | Edges bite into fastener to prevent loosening |
| Wave | Wavy shape, hence the name | Round | Shape compensates spring force, increases load-bearing capacity, absorbs shock and vibrations, and resists loosening and fatigue |
Sources:
https://www.reyher.de/en/download-area/catalogue-fastener-guide
Pub. 1/2018
Please Note:
The product statements contained herein are intended for informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness for a specific application or use. W. W. Grainger, Inc. does not guarantee the result of product operation or assume any liability for personal injury or property damage resulting from the use of such products.